Anti-slack device for crane-operated buckets and the like



D United States Patent l 13,547,276

[72] Inventor Russell B. Thornburg [56] References Cited Palossverdes, Calif. UNITED STATES PATENTS [21] App1.No. 756, 34 I Filed g 30,1968 489,483 l/1893 Kaye 254/153 [45] Patented Dec. 15, 1970 Primary Examiner-Harvey C. Hornsby 73] Assignee b M i Attorney-Christie, Parker and Hale Los Angeles, Calif. a corporation of Delaware ABSTRACT: A s rin -loaded drum cou les a bucket or the 1541 ANTISLACK DEVICE FOR CRANE'OPERATED like through a 110i?! li e to a crane. The tiium is spring-biased BUCKETS AND IKE to exert a take-in force on the hoist line which is less than the 5 3 Drawmg weight of the bucket. When the weight of the bucket is sud- [52] U.S. Cl 212/1, denly taken off the hoist line, the spring rotates the drum to 212/44; 37/ 183; 254/ 150, 254/ 168: 242/107 take in hoist line and prevent its slackening. Thereafter, the [51 Int. Cl B66c 1/00 spring maintains a nominal tension on the hoist line. A stabiliz- [50] Field of Search 212/42, 44, ing sheave is also provided to prevent the rotational moment exerted by the hoist line on the bucket through the drum from upsetting the correct vertical orientation of the bucket.

PATENTEU um 5 I970 SHEET 2 BF 2 I N VENTOR.

ANTI-SLACK DEVICE FOR CRANE-OPERATED BUCKETS AND THE LIKE BACKGROUND OF THE INVENTION The present invention relates to the lifting art in general and, in particular, to an improved device for preventing slack in a cranes hoist line when the weight of its carrying means is suddenly taken from the line. I

In many excavating operations, such as dredging or mining, craneoperated buckets are employed. The bucket is raised and lowered by an operator through a winch. Many styles of buckets are employed including single-line clam shells, double-line clam shells and drag scrapers. In any event, the elevational positioning of the bucket is controlled in the cab by an operator remote from the actual excavation site. In many cases an operator cannot see the area which is being excavated. This handicap is inevitably present, for example, in marine excavation.

In such blind excavating operations an operator can do no more than lower the bucket to the excavating area and wait for it to strike the ground. When the bucket hits the ground the hoist line slackens causing damaging kinking of the hoist line or hoist line fouling. p

Another instance of the problem of line fouling and damage from kinking occurs in ship-to-ship or ship-to-shore material handling. While a crane operator is often able to see the area where his hook is to go, pitching and heavingmay yet cause the hoist line to slacken. I

Therefore, there is a present need for an antislack device for use with buckets or the like to prevent kinking or fouling of the hoist line.

SUMMARY OF THE INVENTION The present invention provides an antislack device to prevent kinking or fouling of a hoist linewhen a bucket or the like suddenly hits the work area.

The present invention provides a spring-biased drum in combination with the carrying means of a crane. The cranes hoist line may be attached to the spring-biased drum for raising and lowering the drum in response to the cranes hoisting equipment. The drum is rotatably coupled to the carrying means which may be, for example, a bucket or a hook. A spring associated with the drum and carrying means biases the drum such that it tends to rotate and take in hoist line. The spring force, however, is less than the weight of the carrying means. This means that hoist line is paid out or spooled out from the drum when the weight of the carrying means is on the hoist line. When the weight of the carrying means is removed from the hoist line, as when the carrying means strikes the ground, the spring rotates the drum to take in or spool in the hoist line and maintain a nominal tension on the line.

In its presently preferred form, the invention provides a stabilizing sheave which is positioned to act against the hoist line above the drum. The sheave is attached to the carrying means such that the rotational moment exerted by the hoist line on the carrying means through the drum is canceled by the reaction moment exerted by the line on the sheave.

In more specific form, the drum has a barrel portion which is journaled to a shaft. The barrel portion houses the biasing spring which is attached to the shaft at 'one end and to the barrel at its other end. A stop is also provided to transfer the weight of the carrying means directly to the hoist line when the hoist line has been paid out. This transfer of the load of the carrying means directly to the hoist line avoids the imposition of the full weight of the bucket on the spring. The stop may be provided by a casing fixed to the shaft around the drum and a collar on the hoist line proximate its point of attachment to the drum. When hoist line is paid out, the collar encounters the casing to transfer the load from the bucket through the casing to the line.

The spring-loaded drum of the present invention may be modified to suit the particular environment in which it is used. Thus, in marine applications it may be desirable to have the biasing spring immersed in oil within the barrel of the drum. The oil may be under pressure to provide a seal. Moreover, depending on the application, a greater or lesser amount of slack must be taken in'by the spring-biased drum. To accommodate a large amount of hoist line on. the drum, it may be necessary to spool the hoist line on the drums barrel for several turns and to overlag line. In this case, it is necessary to insure that when line is paid out, the carrying means does not depart from its acceptable vertical orientation.

The spring-loaded drum of the present invention overcomes the problem of crane hoist line kinking and fouling which has heretofore been attendant in many materials handling environments. The spring in the drum immediately applies a tensioning force on the hoist line when the weight of the carrying means is removed from the line. This tensioning force prevents the kinking. With kinking prevented, hoist line damage and fouling are eliminated.

These and other features, aspects and advantages of the present invention will become more apparent from the following description, appended claims and drawings.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 illustrates schematically a crane and bucket employing the spring-biased drum of the present invention;

FIG. 2 is an end elevation, partly in section, of the springbiased drum of the present invention; and

FIG. 3 is a view taken along line 3-3 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1. illustrates a spring-biased drum in combination with a bucket and crane.

Spring-biased drum 10 is coupled through a shaft 12 to the arms of a bucket 14. A hoist line 16 supports bucket I4 through drum 10. Bucket 14 is operated in the cab of a standard crane 18 by lines (not shown). Hoist line 16 is responsible for the vertical and horizontal positioning of bucket 14. Hoist line 16 is typically controlled by the cranes operator through a winch within the cab.

A stabilizing sheave 20 is attached to shaft 12 and is positioned to urge against hoist line 16 suchthat the rotational moment exerted by hoist line 16 through drum I0 and on bucket 14 is canceled.

The features of the present invention are illustrated in greater detail in FIGS. 2 and 3.

Drum 10 includes a casing 22, a spool 24 and a biassing spring 25.

Casing 22 is fixed to shaft 12 as by welding. Spool 24 is journaled on shaft 12 through a pair of bearings 26. Spool 24 includes a barrel portion 28 which has a cavity 30. Spring 25 is housed in cavity 30 which may be filled with oil to effect a seal.

One end of spring 25 is attached to spool 24 through a radial, outwardly extending flange 32. From this point of attachment, the spring coils about itself for its attachment to shaft 12. The spring is attached to shaft 12 by an inwardly extending flange 34 which is keyed in a slot in the shaft. To provide the amount of spooling capacity normally required and the nominal tension in line 16 desired, spring 25 is preferably a coil or power spring, as illustrated.

Spool 24 includes a pair of circumferential flanges 36 and 38. These flanges guide hoist line 16 such that the line is coiled on itself when it is wound into the drum (as seen in FIG. 2).

Casing 22 has an opening 40 for passage of line 16. Casing 22 forms part of the stop used to transfer the bucket load directly to line 16. This is seen to best effect in FIG. 3. In FIG. 3, line 16 has been paid out by the weight of the bucket. A collar 41 is attached to the line and is sized to abut the inner peripheral surface of the casing surrounding hole 40. The stop is thus effected by the cooperation of collar 42 and casing 22.

FIG. 3 also illustrates the point of attachment of line 16 on spool 24. A clamp member 44 is attached to the spool as by welding. Line 16 is anchored in clamp member 44.

Stabilizing sheave 20 is attached to casing 22 by a pair of arms 46 and 48. An axle 50 extends through these arms and "sheave 20. The sheave is rotatably mounted on this axle. As -seen to best effect in-FIG. 3, line 16, in its paid out state, tends t produce a rotational moment on the bucket through its point of attachment in clamp 44. Stabilizing sheave 20 en- .gages line 16 and transfers the reaction moment from the line through its arms 46 and 48 to the casing. These moments cancel. The cancellation of. the moments prevents undesirable rotation of the bucket.

In operation, bucket 14 is lowered on hoist line 16 from crane 18. While it is being lowered, line 16 is in the FIG. 3

"state; that is, line 16 is paid or spooled out. Line is paid out .fbecause the spring tension of drum is less than the weight of the bucket. The weight of the bucket is transferred through fshaft 12 to casing 22. Collar 42 transfers this load directly to I-hoist line 16. Sheave prevents the bucket from becoming disoriented.

When the bucket strikes the ground, for example, an ex- V cavating site, itsweight will be taken from hoist line 16. After the weight of the bucket is removed from the hoist line, spring .25 spools the line in rapidly. This action of spring on line 16 prevents the lines from kinking.

The present invention has been described in detail with parcan cause a great deal of slackening in the hoist line of the crane employed. The spring-biased drum of the present inven- -tion overcomes the kinking of the hoist line which would otherwise be the result of sudden line slackening. The present invention, therefore, should not be necessarily limited to the foregoing description.

.lclaim:

1. For use with a crane or the like having a hoist line, an improvement comprising:

a. means for carrying a load;

b. a horizontal shaft, the carrying means being carried by the shaft;

c. a drum having a barrel portion journaled for rotation on the shaft, the drum being adapted to spool the hoist line;

d. spring means within the barrel and attached to the shaft and the barrel such that the spring means tends to rotate the drum and spool in hoist line, the spring force of the spring means being less than the weight of the carrying means such that hoist line is spooled out from the drum by the weight of the carrying means until such weight is removed, whereupon the spring means rotates the drum to spool in hoist line and maintain a nominal tension thereon; and

e. stop means operable to transfer the weight of the carrying means directly to the hoist line from the shaft after the hoist line has been spooled out from the weight of the carrying means.

2. The improvement claimed in claim 1 including means to cancel the rotational moment exerted by the hoist line on the carrying means through the drum.

3. The improvement claimed in claim 2 wherein the rotational moment canceling means includes a sheave attached to the load carrying means and disposed such that the rotational moment exerted by the hoist line on the carrying means through the drum is canceled by the reaction moment exerted by the hoist line on the sheave.

4. The improvement claimed in claim 3 wherein the drum has a casing rigidly affixed to the shaft with an opening for the hoist line, the barrel being rotatably disposed within the drum.

5. The improvement claimed in claim 4 wherein the spring means includes a power spring attached to the shaft and the barrel, the power spring being within the barrel. 

